The goal of this research is to understand how the interaction between agonists and their receptors leads to the stimulation of adenylyl cyclase and the induction of tachylphylaxis. Two approaches are being taken. In the one, emphasis is being placed on beta-adrenergic agonists and prostaglandins as they inflence adenyl cylase and receptor function in intact cells (cultured baby hamster kidney fibroblasts), with a view to developing a mathematical model by means of which the response can be described and which may be applicable to all cells which are affected by these agonists. At the same time we are attempting to separate and purify the individual non-receptor components of the adenylyl cyclase system, with a view towards ultimately being able to recombine them to reconstitute the original system. We want to define the basic catalytic subunit common to all mammalian adenylyl cyclase systems, and we are especially interested in understanding the relation between the MgATP-utilizing system found in most cell membranes and the Mn ion-dependent activity which has been found in a few systems. We are also trying to identify the nature and number of regulatory components which influence the catalytic subunit. A series of potential inhibitors of adenylyl cyclase are being tested for possible use as affinity ligands for purification of the enzyme, and we are also planning to use antibodies to pure soluble adenylyl cyclase (from bacteria and testes) for this purpose. Some potentially useful inhibitors have already been found, and we have also found that antibodies prepared against the soluble adenylyl cyclase from B. liquefaciens effectively inhibit adenylyl cyclase from other systems.